Field of the Invention
The present invention relates to a sensing chip package, and in particular relates to a chip scale sensing chip package and a manufacturing method thereof.
Description of the Related Art
A conventional chip package having sensing functions, such as a fingerprint-recognition chip package, is easily contaminated or damaged during the manufacturing processes which results in decreasing both the yield and liability of conventional chip package having sensing functions. In order to meet the tendency of size-miniaturization of electronic components, it is an import subject to minimize the thickness of a substrate for carrying a semiconductor chip to be packaged. However, if a thin substrate for carrying a semiconductor chip to be packaged is utilized, the yield will be reduced owing to the thin substrate is bended or damaged during the package process.
Moreover, the touch panel or the panel having sensing functions, for example biometric identification, are current trends of technology. However, the touch devices are easily out of orders owing to frequently pressing onto the panel by users. In order to resolve abovementioned defects, a scratch-resistant material having a hardness higher than 9, for example sapphire, is selected as the touch pad of the touch panel to protect the semiconductor devices under the touch panel. Currently, the sapphire substrate used to protect the touch devices or biometric sensing devices has a thickness about 200 μm, and the signals of the touch panel or the sensing panel with biometric identification functions are transmitted by the change of touch pad's capacitance. The capacitance of a parallel plate capacitor is well-known as following formula: C=ε*A/d, wherein C is the capacitance of a parallel plate capacitor, ε is the capacitance permittivity of the dielectric material between parallel plates, A is the area of overlap of parallel plates, and d is the distance between the plates. As the capacitance formula of a parallel plate shown, the capacitance is inversely proportional to the distance between the parallel plates when ε and A keep constant. Therefore, the increase of thickness of parallel plates will result in increase of d which leads to decrease of C.
In order to resolve above-mentioned disadvantages and enhance the sensitivity of the capacitive touch panel having sensing functions, this present invention discloses a novel chip scale sensing chip package and a manufacturing method thereof. This present invention is achieved by using a touch plate with a hardness higher than 7 and reducing its thickness to enhance the capacitance of the capacitive touch panel having sensing functions.
Moreover, this present invention is achieved by so-called wafer level package processes, which can not only precisely place the thin touch pad on the sensing chip, but also decrease the thickness of the adhesive sandwiched between the touch plate wafer and the wafer with sensing devices by means of spin coating. Therefore, a high-K material for increasing the capacitance is not necessary and can be replaced by medium-K or low-K materials. Accordingly, the production costs can be reduced, and a chip scale sensing chip package module with higher efficiency are provided. Moreover, the mismatch of the sensing chip and the touch pad occurring in the conventional technology can be avoided because the touch pad and the chip are of the same chip scale by bonding the touch pad to the sensing chip during the semiconductor process.